1. Field of the Invention
This invention relates to the field of prosthetic devices for amputees and more particularly, to the field of prosthetic devices for leg amputees.
2. Discussion of the Background
One of the most difficult problems facing amputees is obtaining a prosthesis (e.g., artificial limb) which can be worn comfortably over a long period of time. This is particularly true for leg amputees as the prosthetic device must bear the user's weight yet avoid applying excess pressure to the critical anatomical areas of the residual limb including the distal end, nerves, veins, bones, and tendons. In doing so, the user's weight is preferably distributed over the greatest amount of residual limb area; and, the contact pressure about and along the weight bearing surfaces of the residual limb is preferably uniform.
In addition to weight bearing, the prosthesis must also maintain alignment and stability of the residual limb by providing lateral support about it. Such support is crucial for proper gait of the user; and, it must be provided without unduly creating pressure on the critical anatomical areas. Equally desirable is the minimization and preferably elimination of any movement and rubbing (shear) between the prosthesis and the user's skin as he or she walks or otherwise moves about. Also, the prosthesis would preferably accommodate minor fluctuations in the volume of the residual limb (e.g., swelling and shrinkage due to, among other things, heat, weight gain or loss, and retention of bodily fluids). These fluctuations are common and affect the critical anatomical areas.
Conventional prostheses are able to accommodate many of the above issues; however, all such prior prostheses sacrifice in one or more areas to provide what is felt to be an optimal balance. These sacrifices often result in an improper fit of the prosthesis with accompanying pain, skin damage to the residual limb, and/or inability to maintain proper attachment of the prosthesis. With the above in mind, the present invention was developed in an effort to accommodate all of these issues.